mbprediction.h

基于Linux的ffmepg decoder

/**************************************************************************
 *
 *  XVID MPEG-4 VIDEO CODEC
 *  -  MB prediction header file  -
 *
 *  Copyright(C) 2002 Christoph Lampert <[e-mail]>
 *               2002 Peter Ross <[e-mail]>
 *
 *  This file is part of XviD, a free MPEG-4 video encoder/decoder
 *
 *  XviD is free software; you can redistribute it and/or modify it
 *  under the terms of the GNU General Public License as published by
 *  the Free Software Foundation; either version 2 of the License, or
 *  (at your option) any later version.
 *
 *  This program is distributed in the hope that it will be useful,
 *  but WITHOUT ANY WARRANTY; without even the implied warranty of
 *  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 *  GNU General Public License for more details.
 *
 *  You should have received a copy of the GNU General Public License
 *  along with this program; if not, write to the Free Software
 *  Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307 USA
 *
 *  Under section 8 of the GNU General Public License, the copyright
 *  holders of XVID explicitly forbid distribution in the following
 *  countries:
 *
 *    - Japan
 *    - United States of America
 *
 *  Linking XviD statically or dynamically with other modules is making a
 *  combined work based on XviD.  Thus, the terms and conditions of the
 *  GNU General Public License cover the whole combination.
 *
 *  As a special exception, the copyright holders of XviD give you
 *  permission to link XviD with independent modules that communicate with
 *  XviD solely through the VFW1.1 and DShow interfaces, regardless of the
 *  license terms of these independent modules, and to copy and distribute
 *  the resulting combined work under terms of your choice, provided that
 *  every copy of the combined work is accompanied by a complete copy of
 *  the source code of XviD (the version of XviD used to produce the
 *  combined work), being distributed under the terms of the GNU General
 *  Public License plus this exception.  An independent module is a module
 *  which is not derived from or based on XviD.
 *
 *  Note that people who make modified versions of XviD are not obligated
 *  to grant this special exception for their modified versions; it is
 *  their choice whether to do so.  The GNU General Public License gives
 *  permission to release a modified version without this exception; this
 *  exception also makes it possible to release a modified version which
 *  carries forward this exception.
 *
 * $Id: mbprediction.h,v 1.1.1.1 2005/09/26 06:07:48 ivan Exp $
 *
 *************************************************************************/

#ifndef _MBPREDICTION_H_
#define _MBPREDICTION_H_

#include "../portab.h"
#include "../decoder.h"
#include "../global.h"

#define MIN(X, Y) ((X)<(Y)?(X):(Y))
#define MAX(X, Y) ((X)>(Y)?(X):(Y))

/* very large value */
#define MV_MAX_ERROR	(4096 * 256)

#define MVequal(A,B) ( ((A).x)==((B).x) && ((A).y)==((B).y) )
/*****************************************************************************
 * Inlined functions
 ****************************************************************************/

/*
 * MODE_INTER, vm18 page 48
 * MODE_INTER4V vm18 page 51
 *
 *   (x,y-1)      (x+1,y-1)
 *   [   |   ]    [   |   ]
 *   [ 2 | 3 ]    [ 2 |   ]
 *
 *   (x-1,y)       (x,y)        (x+1,y)
 *   [   | 1 ]    [ 0 | 1 ]    [ 0 |   ]
 *   [   | 3 ]    [ 2 | 3 ]    [   |   ]
 */

static __inline union VECTOR1
get_pmv_average(const MACROBLOCK * const mbs,
         const int mb_width,
         const int x,
         const int y,
         const int block)
{
	static const union VECTOR1 zeroMV = {0};
    
	int lx, ly, lz;         /* left */
	int tx, ty, tz;         /* top */
	int rx, ry, rz;         /* top-right */
	int lpos, tpos, rpos;

	union VECTOR1 pmv[4];	/* left neighbour, top neighbour, top-right neighbour */

	switch (block) {
		case 0:
			lx = x - 1;	ly = y;		lz = 1;
			tx = x;		ty = y - 1;	tz = 2;
			rx = x + 1;	ry = y - 1;	rz = 2;
			break;
		case 1:
			lx = x;		ly = y;		lz = 0;
			tx = x;		ty = y - 1;	tz = 3;
			rx = x + 1;	ry = y - 1;	rz = 2;
			break;
		case 2:
			lx = x - 1;	ly = y;		lz = 3;
			tx = x;		ty = y;		tz = 0;
			rx = x;		ry = y;		rz = 1;
			break;
		default:
			lx = x;		ly = y;		lz = 2;
			tx = x;		ty = y;		tz = 0;
			rx = x;		ry = y;		rz = 1;
	}

	lpos = lx + ly * mb_width;
	rpos = rx + ry * mb_width;
	tpos = tx + ty * mb_width;

	if (lx >= 0)
	        pmv[1] = mbs[lpos].mvs[lz];
	else 
		pmv[1] = zeroMV;

	if (ty >= 0) {
		pmv[2] = mbs[tpos].mvs[tz];
	} else
		pmv[2] = zeroMV;
    
	if (ry >= 0 && rx < mb_width) {
	        pmv[3] = mbs[rpos].mvs[rz];
	} else {
		pmv[3] = zeroMV;
	}

		/* set median */
	pmv[0].vec.s16x =
			MIN(MAX(pmv[1].vec.s16x, pmv[2].vec.s16x),
				MIN(MAX(pmv[2].vec.s16x, pmv[3].vec.s16x), MAX(pmv[1].vec.s16x, pmv[3].vec.s16x)));
	pmv[0].vec.s16y =
			MIN(MAX(pmv[1].vec.s16y, pmv[2].vec.s16y),
				MIN(MAX(pmv[2].vec.s16y, pmv[3].vec.s16y), MAX(pmv[1].vec.s16y, pmv[3].vec.s16y)));
	return pmv[0];
}

#endif							/* _MBPREDICTION_H_ */